A reliable fabrication technique for very low resistance ohmic contacts to p-InGaAs using low energy Ar+ ion beam sputtering

A fabrication technique for non-alloyed Au/Pt/Ti ohmic contacts to p-InGaAs (NA=1*1020 cm-3) is discussed. The semiconductor surface is cleaned by Ar+ ions immediately followed by the metal deposition by electron beam evaporation. The low energy (60 eV) Ar+ ion etching removes the residual oxide layer existent on the semiconductor surface. The contact is formed by rapid thermal processing (RTP) at 400+or-C. It is shown that extremely low specific contact resistances (rc =6*10-8 Omega -cm2) can be achieved, even for 2.5 mu m contact widths, and that the contacts produced exhibit excellent homogeneity and improved uniformity over wet chemically pre-cleaned ones.